Because cobalt has high conductivity and a high work function, can form a conductive silicide, and has excellent lattice matching with copper, it has gathered attention as a raw material for gate electrodes in semiconductor elements such as transistors, for contacts on diffusion layers in source-drain sections, and for copper wiring sheet layers/liner layers. In next-generation semiconductor elements, highly miniaturized three-dimensional designs are being used to further improve memory capacity and responsiveness. Therefore, in order to use cobalt as a material in next-generation semiconductor elements, a technique is needed to form a cobalt-containing thin film evenly on a three-dimensional substrate to a thickness ranging from several nanometers to tens nanometers. As a technique for preparing a metal thin film on a three-dimensional substrate, utilization of vapor phase deposition method based on chemical reaction such as atomic layer deposition method (ALD method) or chemical vapor deposition method (CVD method) is strongly expected. CoSi2 obtained by forming a cobalt film and then subjecting the film to silicidation is being considered as gate electrodes and as contacts on diffusion layers in the source-drain sections of next-generation semiconductor elements. When cobalt is used as a copper wiring sheet layer/liner layer, a barrier metal such as titanium nitride or tantalum nitride is expected to be used underneath. When silicon or a barrier metal is oxidized in the production of a cobalt-containing thin film, problems such as poor conduction with the transistor due to an increase in the resistance value occur. In order to avoid this problem, there is a demand for a material that enables fabrication of a cobalt-containing thin film under the condition that no oxidizing gas such as oxygen or ozone is used as the decomposition gas.
Non-Patent Documents 1 and 2 mention dicarbonyl [η5-(1-diethylmethylsilyloxy-2,3,4,5-tetraphenyl)cyclopentadienyl]cobalt and dicarbonyl[η5-(1-dimethyl(phenyl)silyloxy-3,4-diphenyl-2,5-dimethyl(phenyl)silyl)cyclopentadienyl]cobalt as compounds having a structure resembling a cobalt complex (1) of the present invention from the viewpoint of having an η5-silyloxycyclopentadienyl ligand, but these differ from a cobalt complex of the present invention from the viewpoint of having a phenyl group. Also, neither of these documents mentions the use of these complexes as a material in the production of a cobalt-containing thin film.